I need to reattach a front sight on a rifle, would plain old 50/50 lead/tin solder be OK to use ? It is a bolt action so the barrel should never get very hot.

Not sure if 50/50 will work, but l know Hi Force 44 will. There is even a high temp version. This stuff is as easy to use as regular soft solder, but will join steel. It's a Brownells producr

Or try JB Weld.

Personally I would not use a solder that melts above 375ºF because you take a chance on messing up the temper of the steel. 60/40 melts at 361º - 374ºF and should work well. 50/50 has a higher melting point and could be as high as 420ºF. There are solders that will fit this bill and that temperature should not produce more than a straw color on raw steel. Obviously the lower the melting point the less strength it will have, however a front sight doesn't need to have the strength of Brazing or welding to stay put. You do not want to change the properties of the metal by over heating!

NOTE: I am not a metallurgist nor a professional GS and I am just posting from the limited experience and knowledge that I have learned informally. Talk to a pro before taking a torch to the metal.

Either will work just fine.
No need to fret over ruining any bbl strength/heat treat.
I've planted 100'ds of sights and scope mt bases onto bbls with sweat solder and never a problem.


I generally use plain old 50/50 or 60/40
I did use the Tin/Silver soft solder on a few but really saw no advantage to it. It's supposed to be a stronger solder than lead/tin. But I've never had a lead/tin solder joint fail. If I need something stronger I use Hard Solder.
I've used Tin/Silver (Hi-Force) to re-lay ribs on SxS bbls as well.
The flow temp is a bit less, but you'll never know it when using a torch to heat things up and watch the parts waiting for the tinned solder to melt and flow.

One thing I don't care for with the Tin/Silver solder is that any line of solder that shows around the solder joint will always remain bright silver color.
Lead/Tin solder will darken as the solder oxidizes to a dark grey color.
A small issue but that bright line even being only a hair thickness can look poor.
You could buy some 'solder black' and color it if you want to.

Tin the part surfaces well no matter which you use.
Fit the surfaces perfectly,,don't expect the solder to be a strong gap filler. It will fill gaps but it will have zero strength.

Flux the tinned part and the barrel surface. Clamp together squarely. Then wipe any excess flux away.
Next take a soft lead pencil (graphite) and scribble the metal surface of the bbl and the part where they meet and anywhere you don't want any solder or flux to attach itself to metal.
The graphite will make any solder or flux that runs out of the soldered joint just roll off the metal..Easy clean up.

Thank you all for the advice.

It is appreciated!

soldering (soft) is not as goog "brazing" which requires skills like a machinest or proper gun smith.

Great instructions 2152hq
Unless it is something real hard like file you will not draw the temper down at 450 or 500.. Barrels are relatively soft. Even springs will not be effected as a springs temper occurred at 750f or above and it will take a temperature above that to change it.

PS You can solder stainless using silver solder (NOT braze), but you need better flux. I use STA-BRITE

If possible machine a small shallow slot in barrel and a corresponding key in sight base for improved strength.

Brownells 44 flows at about 475F. I've used it successfully on quite a few front sights. Even made a fixture to hold the sight in place while soldering, which has always been the hard part, for me at least. If anyone needs a picture, let me know.

__________________
Foster Positivity.

Mauser and the several companies licensed over the years to build their military rifles both small and large ring bolt actions have always soft soldered the sights onto the bbl.
The rear is a sleeve that contains the sight base that is soft soldered onto the bbl just ahead breech.
The front sight also a sleeve base that is soft soldered to the muzzle.
No problems with the system.

SxS shotguns and SxSrifles have their bbls, under lugs and short top rib all attached by brazing on most all assemblys.

The parts are clamped and/or wired up with the braze matrl & flux in the joints. The entire back end of the bbl assembly containing these components (inclu breech end of the bbls) is placed in a furnace and brought to brazing temp to allow the parts to bond together as one piece.

More modern methods use induction coil heat, but the results are the same.

You can see the brazed joints on just about any SxS assembly with a bit of close up inspection.

Here's a set of SxS rifle bbls in 9.3x74R.
You can still see the slight yellow color line in the center of the lug from the braze and the outline of each bbl radius when they were fitted and assembled.




In the second pic you can just barely see the braze seam running along side the locking lug on the bbl flat and on out to the end of the flats.


The claw mount bases are fitted afterwards. The rear base is soft soldered into place on the short rib. The forward base is dovetailed into place an allowed to be moveable for windage.
The bbl ribs are soft solder attached.
All standard stuff.

The Winchester 21 is about the only SxS I can think of that does not braze the tubes w/lugs together. The tubes interlock eachother with a dovetail at the breech. They slide together verticaly and are simply soft soldered. Ribs soft soldered as well.

Some Belgian and Spanish SxS's use Hard Solder to attach the bbl ribs using a furnace process for the needed heat (approx 1100/1200F).
Braze is around 1500F


FWIW
A braze repair on a gun part will hold up through a trip in a re-case coloring. (Not that you would be CC a barrel of course..)
A Hard Solder repair will not.

..Some of the purveyors of the C/Color trade don't like to have a braze repair or any copper/brass bits in their case color boxes as they say it makes the metal box unusable from that point onward.
Others don't have any problems with it.)

I would really like to see it.